This application is based on applications Nos. 2000-222119 and 2000-222130 filed in Japan, the entire content of which is hereby incorporated by reference.
The present invention relates to process cartridge removably insertable in a body of an image-forming apparatus and having constituent elements executing an image formation process and a non-volatile memory storing given information in association with addresses.
In recent years, process cartridges removably insertable in the body of an image-forming apparatus have come into popular use to recycle natural resource as a main purpose. Some process cartridges of this kind have a non-volatile memory storing information about the respective process cartridges, in addition to constituent parts necessary for performing a known electrophotographic process which include a photosensitive drum, a charging unit, an exposing unit, a developing unit, a cleaner, and a toner reservoir.
FIG. 6 of Japanese Patent Application Laid-open No. 2000-19929 shows a memory map of an EEPROM (electrically erasable programmable read only memory) which is a non-volatile memory included in a process cartridge. As apparent from the memory map, data of the same content are stored at a plurality of addresses spaced apart from each other to enhance reliability in data recording. Further, because the amount of shift (xe2x80x9caddress shift amountxe2x80x9d) between adjacent locations storing the same data is constant (32 in the above-mentioned memory map), it is possible to simplify an access program for storing and reading data.
However, the aforementioned constant address shift amount invites a useless increase of usage of addresses, resulting in low storage efficiency. This is inconvenient to the process cartridge because it is difficult to load a memory having a large capacity thereon and also from the viewpoint of costs.
Therefore, it is an object of the present invention to provide a process cartridge having a non-volatile memory storing various data with a preferable data arrangement free from the above-described disadvantages.
Generally, rewritable data is susceptible to errors accompanying a write operation, while read-only data not only is at low risk of errors because of being subject to no write operation, but also has a low degree of importance or significance. In view of this, according to an aspect of the present invention, there is provided a process cartridge removably insertable in a body of an image-forming apparatus, comprising:
a constituent element executing an image formation process; and
a non-volatile memory storing rewritable data having an identical content at a plurality of mutually spaced locations, and each of read-only data (e.g., data indicating a kind of the process cartridge) at locations equal in number to or fewer than the locations for a rewritable data which is assigned a fewest number of locations among all the rewritable data.
The rewritable data may include a counter data that represents a value counted when an image formation process is performed using the process cartridge. The rewritable data may further a detection-of-insertion data indicating whether the process cartridge has been inserted in the body of the image-forming apparatus, and/or a detection-of-new-product data indicating whether the process cartridge is new. The number of locations in the non-volatile memory for the detection-of-insertion data and that for the detection-of-new-product data can be smaller than that for the counter data because both the detection-of-insertion data and the detection-of-new-product data would be read less frequently than the counter data and thus are less susceptible to errors than the counter data.
According to another aspect of the present invention, there is provided a process cartridge removably insertable in a body of an image-forming apparatus, comprising:
a constituent element executing an image formation process; and
a non-volatile memory storing data having an identical content at a plurality of mutually spaced locations in address shift amounts set according to a kind of the data.
Storing one data at a plurality of spaced locations allows another data to be stored between the locations. Thus, it is unlikely that the same data stored at the different locations are simultaneously destroyed. Also, because, with respect the locations for the data of an identical content, an address shift amount from one location to another is set according to the kind of the data, the storage efficiency of the non-volatile memory is increased.
In one embodiment, the address shift amounts are different among a plurality of data that are assigned different numbers of locations in the non-volatile memory. On the other hand the address shift amounts are the same among a plurality of data that are assigned the same number of locations in the non-volatile memory.
In the non-volatile memory, data assigned a single location may be stored at an address prior to an address of a second one of the locations for the data having an identical content. Then, even if the process cartridge is inserted in a test machine in which no rules regarding the data arrangement of the non-volatile memory of the process cartridge are installed, the machine can read out all kinds of data stored in the non-volatile memory before reaching the second location of any of data assigned a plurality of locations merely by sequentially accessing the memory from the headmost address. Thus, the non-volatile memory can be accessed with a simpler control.
According to a further aspect of the present invention, there is provided a process cartridge removably insertable in a body of an image-forming apparatus, comprising:
at least one constituent element executing an image formation process; and
a non-volatile memory sequentially storing, from a headmost address thereof, a detection-of-insertion data indicating whether the process cartridge has been inserted in the body of the image-forming apparatus, a destination data indicating a destination of the process cartridge, and a color code data indicating a color of an image which is formed by the process cartridge.
The process cartridge having the non-volatile memory with such data arrangement allows a control system on the side of the image-forming apparatus body to access the non-volatile memory so as to sequentially read data from the headmost address as follows. First, the control system reads the detection-of-insertion data to determine whether the process cartridge is present in the body of the image-forming apparatus. If it is present, the control system reads the destination data next to determine whether the designated destination of the process cartridge is coincident with a destination data of the image-forming apparatus""s own. The determination result indicates whether the process cartridge matches the body of the image-forming apparatus. If the process cartridge is determined to match the body of the image-forming apparatus, then the control system reads the color code data to determine whether the process cartridge is placed in position in the image-forming apparatus body (for example, in a station for a color matching the process cartridge). Only after the process cartridge is determined to be in position in the image-forming apparatus body, it is determined that the process cartridge has been properly inserted in the body of the image-forming apparatus. Thereafter, the control system of the image-forming apparatus is allowed to start various control operations for image formation using the process cartridge.
As can be understood from the above, the control system of the image-forming apparatus side is not required to have a table storing the order of access to addresses of the non-volatile memory, but is allowed to access sequentially the addresses of the non-volatile memory from the headmost one. Thus, this data arrangement in the non-volatile memory contributes to simplification of the control by the control system of the image-forming apparatus body regarding the access thereto. This is true also when the process cartridge is inserted in a test machine before its shipment or after its recovery or return.
To have the destination of the process cartridge checked in detail, the destination data may include, in order of address, a shipment destination data indicating a destination classified by region and an OEM code data indicating an OEM for which the process cartridge has been manufactured.
Generally, a density adjustment for the process cartridge is required to precede the other controls for the image formation operation to achieve color balance with other process cartridges placed in the body of the image-forming apparatus. To satisfy the requirement, in one embodiment, the non-volatile memory contains a detection-of-new-product data indicating whether the process cartridge is new at an address subsequent to the address at which the color code data is stored. The control system of the image-forming apparatus will read the color code data only after determining the non-volatile memory has been properly inserted but before starting the control for the image formation operation using the process cartridge. When determining that the process cartridge is new, the control system is allowed to perform a density adjustment operation for the process cartridge before starting the control for the image formation using the process cartridge.
To facilitate production of the process cartridge, the at least one constituent element of the process cartridge may include a photosensitive unit including a photosensitive drum, a charging device, and a cleaner, and a developing unit including a developing device and a toner reservoir.
Other objects, features and advantages of the present invention will be obvious from the following description.